OK, here's the deal. No brake or it doesn't hold.

Fresh transmission.
At idle, Pressure at the servo 200+ lbs. Put it in reverse 200+ at the port. Put it in low and hit the TB button reverse goes to zero, servo stays at 200. Pressure makes a blip at the reverse pressure port but drops to zero.
Valve body?

Dave

Dave, is it a pro brake or a full tree brake? Does reverse work?

Years ago I had a torn valve body gasket. Transbrake worked in low gear but if you put it in reverse it would not back up. You might check your gasket.

quote:

Originally posted by David Covey:
OK, here's the deal. No brake or it doesn't hold.

Fresh transmission.
At idle, Pressure at the servo 200+ lbs. Put it in reverse 200+ at the port. Put it in low and hit the TB button reverse goes to zero, servo stays at 200. Pressure makes a blip at the reverse pressure port but drops to zero.
Valve body?

Dave

All pressure should be checked at 2200rpm. Do that an see what it is and report back. Likely torn seal somewhere.

quote:

Originally posted by Larry Woodfin:
Dave, is it a pro brake or a full tree brake? Does reverse work?

It's supposed to be a pro brake. Reverse does work. When you shift to reverse you have pressure even when you set the brake. Just when you are in low and set the brake the pressure goes away.

Dave

quote:

Originally posted by Cashflow:
Years ago I had a torn valve body gasket. Transbrake worked in low gear but if you put it in reverse it would not back up. You might check your gasket.

No gasket.

Dave

quote:

Originally posted by ski_dwn_it:

quote:

Originally posted by David Covey:
OK, here's the deal. No brake or it doesn't hold.

Fresh transmission.
At idle, Pressure at the servo 200+ lbs. Put it in reverse 200+ at the port. Put it in low and hit the TB button reverse goes to zero, servo stays at 200. Pressure makes a blip at the reverse pressure port but drops to zero.
Valve body?

Dave

All pressure should be checked at 2200rpm. Do that an see what it is and report back. Likely torn seal somewhere.

He took the trans out last night and put his spare back in. I will tear it down again and check.
Part of the issue is he bought this transmission used and has never ran it, so we do not know if it had a problem before. I went through it and replaced the seals and checked it out before he put it in.

Dave

For my taste 200 psi is low for a Transbrake trans. Regardless when you tear it apart, take a close look at the reverse clutch piston seals and case area where they are applied. For sure air check before pulling it completely apart

Which govenor support does it have in it? Is it possible the block off plate was not put back in between the govenor support and the case?

quote:

Originally posted by 329L:
Which govenor support does it have in it? Is it possible the block off plate was not put back in between the govenor support and the case?

Aluminum roller bearing, Dedenbear case.

Dave

quote:

Originally posted by Big Steve:
For my taste 200 psi is low for a Transbrake trans. Regardless when you tear it apart, take a close look at the reverse clutch piston seals and case area where they are applied. For sure air check before pulling it completely apart

It has more than that, it's just what the gage is capable of reading. Way past the 200lb mark. And just to answer Ski's statement the pressure was at idle raise the rpm and pressure increased.
This is an aluminum VB thinking changing the boost valve and spring will not have an effect on pressure. Never tried that one.

Dave

if it has the wrong rear cover or no plate it can do that ,329 is right.if you are at 220 lbs changing the spring will not correct the issue you have

If it has a billet support than it should be fine. Just ran into this issue over the weekend, a guy bought a dragster trans, converted it to a long shaft, used a stock governor support without a plate and did all kinds of stupid ****t.

After actually re reading the original post, i have seen a severly undersized/scratched/destroyed spool valve cause an issue like that.

Thanks guy's. I'll let you know what I find when he brings it over and I get it checked/torn down.

Dave